1. Field of the Invention
The present invention relates to the field of power transferring devices of the type used to regulate or control the application of alternating current electric power to a load such as a motor, a heater, an instrument, or another device consuming electrical power. Typically such regulation or control of electric power is either manually adjusted according to precalibrated settings, or is automatically provided in response to a sensed load condition such as voltage, current, temperature, speed, humidity, or the like.
More particularly, the present invention relates to power transferring devices of the controlled reactance type inserting a variable reactance in a circuit to control the flow of power.
2. Description of the Prior Art
Various known arrangements utilize controlled reactances in order to provide controlled power transfer. One well known arrangement, providing independently controlled saturation of a reactor in response to a control signal, is described in various forms in the following U.S. Pat. Nos. 2,767,364; 3,061,770; 3,182,249; 2,497,218; 3,065,399; 3,263,158; and 2,725,508. Other known arrangements continuously vary reactance of a primary coil by varying the impedance of a secondary, as shown for example in U.S. Pat. No. 2,907,946.
These known arrangements have not proven entirely satisfactory. Although they control power transfer, they often require complicated, power-consuming controls which add cost and reduce efficiency in terms of power transfer. Such devices function to vary reactance by controlling the extent of magnetization to the point of saturation of a reactor core, and thus their performance is strongly influenced by the magnetization characteristics of the magnetic materials used and at times by the history of prior magnetization.